This invention relates generally to devices known as centralizers for use in centering a string of tubing in a well. Heretofore it has been common practice to incorporate centralizers into a tubing string located in a well to insure that the tubing string does not contact the well wall or, if the well is cased, the casing. In many instances centralizers were used when it was desired to prevent heat loss or gain between the centralized tubing string and the well casing. Thus when steam or other hot fluid is injected into a formation it is desirable to prevent contact between the tubing string used for steam injection and the well casing to prevent excessive heat loss from the injection string. Similarly in permafrost areas it is desirable to prevent heat from a production or injection string from melting the permafrost. Heretofore metal centralizers have been used to overcome these problems. However, there has not been a completely satisfactory centralizer for such use due to the high heat conductance of the metal. Further, the prior art centralizers being made of metal are very difficult to remove by milling or washing over if the tubing string becomes stuck.